I'm afraid water might get in there somehow. Plus its looking really dusty.

Any reason why I shouldn't?

I pre-filter will still get wet and soak though. Do you have air scoops? That is probably the reason for all the dust. I would not worrk about water.....at speed no water would go though the vents, and sittintg still looks like it would drain over the power steering resivoir and not the filters.

If it makes you feel better, I have a cone filter peaking out of the inlet of my front bumper, it's exposed to everything.